The present invention relates to panel attachment members and more particularly concerns an expansion sleeve which is more readily and securely affixed to a relatively thin panel member or plate.
Various types of blind rivets, expansion sleeves and other types of expandable fasteners have been employed for many years for attachment of objects to thin panels or plates. These devices often include elements adapted to extend radially outwardly of the fastener along the interior of the panel or plate.
Where the structure to which the fastener is to be attached is solid, or backed with a solid material such as a solid concrete wall or member or roof structure, expansion sleeves are secured by means of the frictional force exerted between internally expanded portions and the relatively thick solid structure.
Many types of structural panels are composite structures, formed of a core or backing material and an outer cover or facing sheet. For example, in a construction known as Robinson Decking, which is commonly used for lightweight flooring, a corrugated rigid sheet metal panel is employed as the bottom facing sheet of a floor upon which a lightweight porous concrete is poured to provide a suitable floor support. The corrugated sheet metal panel becomes the ceiling for areas below the decking and is used to support various types of suspended structures such as conduits, water pipes, electrical lines, or platforms for suspended equipment such as air conditioners, fans, heaters or the like.
The lightweight concrete of such composite structural panels does not have sufficient strength to hold a conventional expansion sleeve since such concrete is readily crushed by pressures that would be exerted by such a sleeve. Yet, the presence of such concrete will prevent the use of conventional thin wall fastening devices that require radial expansion along the interior of a plate or thin wall panel. Moreover the upper surface of the concrete decking must remain undisturbed, entirely free of holes for fasteners.
It is possible to pre-drill holes in the corrugated sheet metal of such composite decking and insert headed bolts into such holes to hang from the decking before the pouring of the concrete. However, this arrangement requires that all of the necessary and desired support points be located before the pouring of the concrete and, further, does not permit any change in location of points or addition of other supported equipment without drilling through the upper surface of the concrete. It is often desirable to locate equipment and devices to be supported from such overhead composite decking after the decking has been completed, but no simple or adequate techniques for attachment of devices to such decking are presently available.
Accordingly, it is an object of the present invention to minimize or avoid above-mentioned problems.